There are many types of endotracheal tubes known to the medical profession, and many types of known apparatus intended to keep the tubes in place in the patient's oral cavity and trachea. We have found that the apparatus that currently is available have deficiencies that not only cause discomfort to the patient, but also have life threatening consequences. Sustained lateral and/or axial movement of a tracheal tube results in irritation, and possibly ulceration, of the lips, tongue, and trachea, including the vocal cords of the patient.
Oral bite pieces that engage the endrotracheal tube have been provided in an attempt to hold the tube in a fixed position in the patient's mouth and to prevent the patient from biting the tube and blocking or severing it. The bite pieces are ill-fitting and cause extreme discomfort to many patients.
Of even more serious consequences are the deficiencies of the materials selected for use in manufacturing the tubing. Some of the plastic materials used for making endrotracheal tubing are not heat stable in their physical characteristics at body temperatures and do not remain firm enough at those temperatures to retain their desired shapes while being inserted, and while in place. Sometimes a tube will collapse and/or kink, causing irritation if left in place, and more importantly, significantly reducing the rate of flow of air, oxygen mixture, etc., that can flow through the tube. The total volume of fluid flow per unit of time through a tube is given by Poiseuille's law as follows. ##EQU1## V=volume of flow. R=radius of the tube.
p.sub.1 and p.sub.2 are the pressures at the respective ends of the tube. PA1 n=viscosity of the flowing fluid. PA1 L=the length of the tube.
From this equation it is seen that any slight restriction in the radius R of the tube can have a significant reduction in the rate of flow through the tube since the radius is raised to the fourth power.
Additionally, it is seen that the rate of flow is inversely proportional to the length of the tube. Therefore, for a weak patient who does not have the strength to overcome any significant resistance to breathing, not only must the tube remain uniform in cross section throughout its length, but the tube must be as short as possible. These basic physical considerations seem not to have been previously taken into consideration in the construction and method of administering the intubation of endotracheal tubes.